all clients will get the latest version of the row (from RAM, that is). The only thing is that in case of server crash, not-yet-written-to-disk commits will be lost.
To improve commit performance we are planning to use "synchronous_commit=off", with this if multiple clients are reading the same data/row will they always get the latest updated data/row ? (clients are using committed read and we are not using clustered environment, we have just one instance of postgres serving local clients running on the same machine). For example if client1 updates a row then the updated value is available to client2 immediately after the commit or there is a delay as commit is now asynchronous ?